1. Field of the Invention
The invention relates to a de-interlacing device and a method therefor, and more particularly to a de-interlacing device having a pattern recognizing unit and a method therefor.
2. Description of the Related Art
The typical film is shot and played in an interlaced manner. In a television, for example, the playing procedures of one frame thereof include a playing procedure of an odd field and a playing procedure of an even field. The odd field is composed of the odd-numbered display lines of the frame, and the even field is composed of the even-numbered display lines of the frame.
The refresh rate of the typical television is 30 Hz. That is, 30 frames are played in one second. Each frame are played with the odd field and the even field, so 60 fields are played in one second.
Because the requirement on the image quality is getting higher and higher and the quality of the non-interlaced (also called as progressive) image is better than that of the interlaced image, the more advanced image playing device, such as a high-definition television (High Definition TV, HDTV), has the progressive playing function.
If the interlaced image is to be played in the non-interlaced manner, the interlaced frame has to be de-interlaced into a complete frame, which is then played. FIG. 1A is a schematic illustration showing an interlaced image, which includes a (n−1)-th field, an n-th field and a (n+1)-th field. In the example of FIG. 1A, descriptions are made with reference to the pixels having the x coordinates of (i−1) to (i+1) and the y coordinates of (j−1) to (j+1). Each field of the interlaced image only includes the odd-numbered or even-numbered horizontal lines to be displayed. So, only the pixels in the odd-numbered or even-numbered horizontal lines have effective values in each field, wherein the pixels marked with “X” represents that the no effective luminance value exists in this field. De-interlacing the interlaced image is to fill proper luminance values into the pixels without effective luminance values in each field. Taking the time average method as an example, the luminance value of the pixel (i,j) in the non-interlaced n-th frame may be the average of the luminance values of the pixel (i,j) of the interlaced image in the (n−1)-th and (n+1)-th fields. According to the above-mentioned method, the n-th frame of the non-interlaced image may be obtained, as shown in FIG. 1B.
However, the de-interlacing method tends to cause errors in the displayed image because the two fields of the interlaced image are shot at different time instants, and the image quality cannot be enhanced until the image is further processed.